I found Mobile Read through a google search the day I bought my reader, and don't think I've left since...
I heard via the yeti that Smiths were selling the CyBook at a reasonable price - I'd originally wanted an iLiad, but the price was too offputting. So we went on a hunt to see if Smiths had any in store we could look at and discovered they don't keep them in stores. Next to the second Smiths we looked in was a Waterstones, with the Sony 505 on display. I promptly fell in love with it and we both bought one. The yeti since discovered he doesn't like reading off a screen and far prefers physical books so sold his. Being able to carry lots of books in something that weighs so little was a major factor for me, as was being able to read easily whilst standing on the tube, holding on with one hand!